1. Field of the Invention
The present invention relates generally to an apparatus and method for classifying images, and more particularly, to an image classification apparatus and method for determining whether an input image is a monochromatic image or a non-monochromatic image and applying Automatic White Balance (AWB) to the non-monochromatic image.
2. Description of the Related Art
Generally, a white object is viewed in a color different from its original color according to the light source such as the sun, a fluorescent lamp and an incandescent lamp. AWB is an image technology proposed to adjust images so that the white object can be viewed in a white color. Regarding adaptability to colors, a human being may not perceive a difference in color for an object when there is a change in illumination and/or location. However, a conventional camera, which does not perceive and process objects in the same manner as a human being, may perceive a difference in color for an object according to the illumination and location. Therefore, the AWB technology is used to control a phenomenon that a color changes according to the light source in the camera.
The AWB technology is classified according to estimation of a light source. An AWB technology that estimates a light source adjusts a gain of each channel by finding a white region(s) of an input image and using an average of Red-Green-Blue (RGB) values of image information or an average of color difference signals (R-Y) and (B-Y), which correspond to the adjusted gain. An AWB technology that does not estimate a light source adjusts a gain of each channel using an average for each channel over the entire image. In these technologies, when an input image has a sufficient color change, a color consisting of an average for each channel is assumed to be a gray color. That is, it is possible to recover white balance of an image by adjusting gains of RGB values of the image so that an average for each channel is equal.
Conventionally, in this way, AWB is applied to an input image that has a sufficient color change or a white region.
However, if AWB is applied to an input image that is determined as an image having a color change, but does not actually have a sufficient color change or if AWB is applied to an input image that does not have a white region, like a large monochromatic object or a monochromatic background, then the color of the image may be distorted by the AWB.